Fuses incorporated into the electronic circuitry of automotive vehicles comprise a pair of coplanar blade terminals that extend from a nonconductive fuse housing. Portions of the blade terminals disposed within the fuse housing are electrically connected to one another by a fuse wire that enables a circuit to be completed across the planar blade terminals. The fuse wire, however, is designed to break when subjected to current levels in excess of a pre-established maximum. The breaking of the fuse wire will break the circuit into which the fuse is incorporated, thereby preventing the high current levels from damaging the essential and/or expensive electrical components incorporated into the particular circuit of the vehicle's electrical system.
The planar blades of the automotive fuse are mated to a pair of terminals in a fuse socket. The terminals of the fuse socket include contact areas disposed adjacent to a fuse cavity in the socket housing. Thus the planar blade terminals of a fuse inserted into the fuse cavity will be electrically contacted by the terminals of the socket. The fuse socket or fuse block typically will be mounted to a circuit board having an array of circuits printed or otherwise disposed thereon. The fuse engaging terminals of the socket may thus include solder tails or other such electrical connection means for electrical connection to the circuits on the board.
It is essential that a high quality electrical connection to a fuse be maintained during all ranges of temperature, vibration and shock to which a vehicle is subjected. This high quality electrical connection may be achieved by providing high normal contact forces between the blade terminals of the automotive fuse and the terminals of the socket into which the automotive fuse is inserted. A high quality electrical connection also can be achieved by providing a large contact area between the respective terminals of the fuse and the socket.
Each terminal of a typical prior art automotive fuse socket includes a rear longitudinal end defining means for mounting to a circuit board, an intermediate portion for secure engagement in the fuse socket housing and a mating end for engaging a planar blade terminal of a fuse. The mating end of the typical prior art automotive fuse terminal is defined by a pair of cantilevered leafspring contact beams which are formed to converge toward one another and define contact surfaces at a minimum dimensioned gap therebetween. The contact surfaces of the prior art terminal will be substantially parallel to one another and will define a spacing that is less than the thickness of the fuse blade. Thus, the cantilevered contact beams will deflect symmetrically about parallel axes upon insertion of the fuse into the socket. The resiliency of the metal from which the prior art terminal is formed will cause the deflected cantilevered contact beams to exert contact forces against the planar fuse blade.
Although the prior art blade engaging terminals of this type have performed fairly well, it is desirable to provide higher contact forces for achieving better electrical connection during all ranges of shock, vibration and temperature to which an automotive vehicle is subjected. More particularly, it is difficult to design the prior art cantilevered leaf-spring contact beams to achieve higher contact forces without substantially increasing the size of the terminal. Larger terminals typically require more metal, and therefor are more costly. Additionally, the continuing trend toward miniaturization substantially prevents the use of larger terminals.
An extremely desirable automotive fuse connector is shown in U.S. Pat. No. 4,943,248 to Colleran et al. which is assigned to the Assignee of the subject application. U.S. Pat. application Ser. No. 4,943,248 shows and efficient fuse terminal that is stamped and formed to have contact surfaces defined by edge regions of the metal. With this construction, the contact beams will deflect about axes extending orthogonal to the plane of the metal, and will thereby generate very high normal contact forces for positively retaining the fuse during extreme conditions of vibration and shock. Despite the many advantages of the terminal shown in U.S. Pat. No. 4,943,248 , it is desirable to provide an automotive fuse engaging terminal that will provide a large contact area while still achieving high contact forces.
The recent prior art includes unitarily formed pin engaging terminals having a pair of opposed deflectable contact beams extending from a base and having a deflectable assist structure extending between portions of the contact beams remote from the base. The assist structure of these prior art pin engaging terminals may be generally U-shaped or generally in the shape of a tuning fork. Examples of such terminals are shown in U.S. Pat. No. 4,907,990 to D. Bertho et al. and U.S. Pat. application No. 4,900,271 to S. A. Colleran et al., the disclosures of which are incorporated herein by reference. The insertion of a pin into these prior art terminals will generate deflection of both the contact beams and the assist structure, such that the assist structure contributes to the contact forces exerted by the beams.
Co-pending Pat. application Ser. No. 441,674 now U.S. Pat. No. 4,968,270 was filed by Stephan Colleran and Robert Gugelmeyer and is assigned to the Assignee of the subject application. This co-pending application is directed to a socket for receiving a low wattage bulb intended for use in an automotive instrument panel. Bulbs of this type include a pair of thin deflectable leads which must be engaged by the terminals in the socket. The socket shown in this co-pending application includes terminals that employ the above described tuning fork assist structure. However, the contact beams of the terminals in this bulb socket are concavely arcuate from side to side to efficiently capture and align the leads of the bulb with the contact beams of the terminal in the bulb socket. The tuning fork assist structure contributes to the contact forces exerted against the leads of the bulb. The disclosure of this co-pending application also is incorporated herein by reference.
An entirely different terminal for engaging a pin, as opposed to a blade, is shown in U.S. Pat. No. 4,772,234 which issued to Cooper on Sept. 20, 1988. The terminal shown in U.S. Pat. No. 4,772,234 includes a generally box-shaped mating end that is intended to undergo a complex twisting upon insertion of a generally square pin. This twisting of the initially box-shaped mating end will cause the terminal to achieve small points of contact with the corners of a square pin inserted therein.
In view of the above described prior art, it is an object of the subject invention to provide an automotive fuse connector for achieving high quality electrical connection to the planar blade terminals of an automotive fuse.
It is another object of the subject invention to provide electrical terminals for use with planar blade terminals, such as the planar blade terminals of an automotive fuse.
It is a further object of the subject invention to provide blade receiving terminals that provide a large contact surface and high normal contact forces.
An additional object of the subject invention is to provide terminals having opposed non-parallel contact surfaces that deflect into parallel alignment with one another upon insertion of a blade terminal therebetween.